Looks like the online Recorder of Deeds has records back to 1973 and up to pretty-current date.  They require a free subscription to log in, whereby they provide you with a password access.

They allow you to order docs online for whatever their fees are set at.

They have their UCC / Financing Statement system online too.

Their online Assessors and Property Sales database looks public (no subscription/pass required) and fairly comprehensive.  It appears to be the same as their online tax roll, so the two are one.

I would say to try HomeInfoMax.com or one of the other DataTree-derived information providers to get a chain that can then be verified and expounded upon using the DC online resources. 

Doesn't look too complex and easier than those counites with nada online.